STATEWIDE UPDATE: New California ADU Bills SB13, AB68, AB881, AB670 have passed. These laws will create more options for building an ADU in Redwood City in 2020. To prepare for the upcoming changes use our ADU Services to learn how these laws will effect your property!
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Last Updated 11/04/19


The city government of Redwood City will approve ADUs under California's statewide mandated regulations.
The California Building Code (CBC) 2016 is adopted with the following amendment(s): 2428 to 2429
Relevant state bill updates for SB13, AB68, AB881, AB670 are shown in green below.


City Hint: The city has not yet responded to requests for ADU permit volumes for the past year, but they will be provided here once response has been received.


Number of ADUs allowed:

One ADU per primary home.

AB68 & AB881 Update: Properties which convert existing space to create ADUs may be eligible for one ADU -AND- one JADU.

Types of ADUs allowed:

Detached, Attached, junior ADU.

Lot size:

Minimum Net lot area. (A) R-0 and R-1 zoning districts require eight thousand five hundred square feet. (B) R-2 zoning district and residential DSP blocks require five thousand square feet.

AB68 & AB881 Update: Properties will not be subject to minimum lot standards by ordinance or of the applicable zoning district.

ADU size:

The maximum allowable floor area for an ADU may be increased from 640 square feet to 700 square feet if an ADU is constructed to meet the California Building Code requirements for disabled access.

AB68 & AB881 Update: Properties will be allowed up to 850 square feet for a one bedroom or up to 1,000 square feet for a two bedroom ADU.


Setbacks of an ADU that is attached to or detached from the main house shall be subject to the minimum setback standards of the underlying zoning district. Additionally, minimum setback of six (6) feet shall be required between an accessory dwelling unit and any single-family dwelling or accessory buildings on the lot.

AB68 & AB881 Update: The maximum required setback for a detached new construction ADU shall be no more than 4 feet from the rear or side property lines.


One covered or uncovered space shall be required for the ADU. If uncovered, the ADU parking space may be located on a driveway within a required front, side or rear yard setback area. Tandem parking to meet the ADU parking requirement is permitted.

AB68 & AB881 Update: Properties which convert an existing garage will not be subject to replacement parking requirements.

Fire Safety:

Fire sprinklers shall be installed for the ADU.

Shape, materials and style:

An accessory dwelling unit shall be architecturally compatible with the architectural style and exterior paint and materials of the single family dwelling on the same lot.


Maximum building height is 28 feet and structures shall not exceed 2.5 stories. The building height of a detached accessory dwelling unit shall not exceed the building height of a single-family dwelling on the same lot.

Design review:

Ministerial review process.

Number of Bedrooms:

Up to one (1) bedroom shall be permitted.


The accessory dwelling unit shall not be intended or offered for sale, nor sold, but may be rented. The property owner shall live on-site in either the main unit or the accessory dwelling unit.

SB13 Update: Owner-occupancy requirements for ADUs will be voided statewide for 5 years.

Utility connections:

shall be exempt from the requirement of upgrading a water main.

Permit Fees

SB13 Update: Local impact fees for ADUs will be reduced substantially statewide.


An accessory dwelling unit, commonly known as a second unit or in-law unit, is an attached or detached dwelling unit that is located on the same lot as a single family dwelling and provides complete living, sleeping, eating, cooking, and sanitation facilities
separate and independent of the main dwelling.


For lots that are greater than or equal to 10,000 square feet in the Residential Hillside (RH) or Residential Single-Family (R-1) Zoning Districts, the maximum allowable floor area for an ADU shall be 800 square feet and no more than two (2) bedrooms.

The homeowner may live offsite and rent out both the main house and the ADU due to:
a. A medical condition that requires residency elsewhere; or
b. The homeowner accepts a job transfer outside of the San Francisco Bay Area.

A detached ADU may be built within a required rear yard setback area provided that the ADU meets the following requirements:
a. Minimum Rear Yard Setback: 10 feet
b. Maximum Building Height: 14 feet
c. Maximum Wall Height: 9 feet
d. No more than 50% of the required rear yard setback area shall be covered by structures.

Allowed Zones:

An Accessory Dwelling Unit (ADU) may be built on the same property as an existing or proposed single-family residence in the RH, R-1, R-2, R-3, R-4, and R-5 zoning districts.

AB68 & AB881 Update: ADUs will be allowed statewide in all single-family or multi-family zoning districts.

Open Space:

The front yard shall be subject to the minimum pervious area and stormwater requirements of the underlying zoning district.

Lot Coverage:

Total lot coverage is limited to 40 percent of the lot area. Not more than 40 50 percent of the required rear yard shall be covered by any combination of accessory buildings or an accessory dwelling unit subject.

Residential Building Code:

The California Building Code (CBC) 2016 is adopted with the following amendment(s): 2428 to 2429

Redwood City City Planning Offices

Redwood City Planning Division

Contact Planner Diana O'Dell. Counter Hours: 8AM-5PM (M/W/F), and 12:30PM-5PM (T/Th) (walk-ins welcome)

1017 Middlefield Road Redwood City, CA 94063

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Nikki James

Opes Advisors

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Contact Nikki James about ADUs in Redwood City. Send a text message:

Redwood City ADU Marketplace

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Program Representative

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Costs / ROI


* upon completion of ADU


* based on local average price per sqft


* estimated by location


* 30 years / 5% interest rate / 20% down payment


Appreciation Estimate = (Base Value: $) / (Home's Living Space: sqft) * (ADU's Living Space: sqft)

Rental Estimate = (Rent Per Sqft: $5.24) * (ADU's Living Space: sqft)

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